Paying off already

David Rhodus imported Hyperthreading changes from FreeBSD which allow you to automatically use Hyperthreading on supported CPUs with just the regular multiprocessor options turned on in your kernel; e.g. options SMP, options APIC_IO.

However, the DragonFly version has no idling loops in it to reduce CPU resource contention. Because of the way DragonFly schedules per-CPU/sends IPI messages, there’s no performance issue caused by multiple CPUS HLTing. Already, a benefit.